NMR studies of nucleotide conformation and nucleotide interactions concentrated on the elucidation of structure of the associated form of guanosine-5'-phosphate at neutral pH. Related theoretical studies showed that account must be taken of lone-pair electron repulsions in the 3'-5' O-P-O linkage of polynucleotides. A new multi-nuclear NMR spectrometer was completed and placed in operation, and significant technical improvements were introduced, especially in the study of dilute aqueous solutions.